Method of making automotive trim

ABSTRACT

An automotive trim material to be detachably mounted on a painted steel automotive body by means of clips secured to the body is shown to comprise a composite metal laminate material having an outer layer of stainless steel disposed exteriorly of the trim configuration, an intermediate layer of mild steel material, and an opposite outer surface layer of aluminum material, said laminate layer materials being metallurgically bonded together in the solid phase, the stainless steel layer being in scratch-resistant, cold-worked condition, the mild steel layer being in easily formed, annealed condition, and the interface between the mild steel and the aluminum layers being substantially free of embrittling aluminum-iron intermetallic compounds. The composite metal laminate material is formed by roll-squeezing layers of selected metal materials together with reduction in the thicknesses thereof at a temperature below the temperature at which a liquid phase of the layer materials is formed and below a temperature at which intermetallic compounds of aluminum-iron are formed, thereby metallurgically bonding the layers together and cold-working the layer materials. The resulting bonded composite material is then heated to a selected temperature which is above the recrystallization temperature of said mild steel material, which is below the recrystallization temperature of said stainless steel material, and which is below the temperature at which any substantial amount of aluminum-iron intermetallic compound is formed at the bonded interface between the mild steel and aluminum materials of the laminate.

United States Batent Anderson 1 1 Mar, 114, 1972 [72] Inventor: Ray B.Anderson, Attleboro, Mass.

[73] Assignee: Texas Instruments Incorporated, Dallas,

Tex.

[22] Filed: Jan. 2, 1970 [21] Appl. No.: 478

[52] U.S. Cl ..29/470.1, 29/4723, 29/487,

29/4975, 29/504, 29/1916, 29/1961 [51] Int. Cl ..B23k 21/00 [58] Fieldof Search ..29/4701, 4723, 497.5, 504,

[56] References Cited UNITED STATES PATENTS 1,984,134 12/1934 Himmel etal. ..29/19l.6 2,484,118 10/1949 Reynolds ..29/196.2 X 3,536,459 10/1970Bates ..29/191.6 3,556,745 1/1971 Zaremski ..29/19l.6 X 3,559,276 2/1971Anderson ..29/4975 X 2,691,815 1011954 Boessenkool et al.. ..29/470.1 UX2,704,883 3/ 1955 Hamilton et a1. ..29/472.3 X 2,937,435 5/1960 Brenneret a1. ..29/504 X 2,965,963 12/1960 Boty et al ..29/497.5 X 3,078,5632/1963 Gould et a1. 3,393,445 7/1968 Ulam 3,352,005 11/1967 Avellone..29/504 X 3,381,365 5/1968 Winter ..29/4723 3,387,357 6/1968 Sendzimir..29/4975 X METHOD OF MAKING AUTOMOTIVE TRIM Primary ExaminerJohn F.Campbell Assistant ExaminerRonald .1. Shore Attorney-Harold Levine,Edward J. Connors, Jr., John A.

Haug, James P. McAndrews and Gerald B. Epstein [5 7] ABSTRACT Anautomotive trim material to be detachably mounted on a painted steelautomotive body by means of clips secured to the body is shown tocomprise a composite metal laminate material having an outer layer ofstainless steel disposed exteriorly of the trim configuration, anintermediate layer of mild steel material, and an opposite outer surfacelayer of aluminum material, said laminate layer materials beingmetallurgically bonded together in the solid phase, the stainless steellayer being in scratch-resistant, cold-worked condition, the mild steellayer being in easily formed, annealed condition, and the interfacebetween the mild steel and the aluminum layers being substantially freeof embrittling aluminum-iron intermetallic compounds. The compositemetal laminate material is formed by roll-squeezing layers of selectedmetal materials together with reduction in the thicknesses thereof at atem' perature below the temperature at which a liquid phase of the layermaterials is formed and below a temperature at which intermetalliccompounds of aluminum-iron are formed, thereby metallurgically bondingthe layers together and cold-working the layer materials. The resultingbonded composite material is then heated to a selected temperature whichis above the recrystallization temperature of said mild steel material,which is below the recrystallization temperature of said stainless steelmaterial, and which is below the temperature at which any substantialamount of aluminum-iron intermetallic compound is formed at the bondedinterface between the mild steel and aluminum materials of the laminate.

41 Claims, 2 Drawing Figures METHOD OF MAKING AUTOMOTI\E T A materialproposed for use as automotive trim and the like comprises a compositemetal laminate material having an outer layer of stainless steel, anintermediate layer of mild steel, and an opposite outer layer ofaluminum material, the layers of the composite being metallurgicallybonded together along the interfacial surfaces between the metal layers.When this composite material is formed into a selected trimconfiguration with the stainless steel layer of the composite disposedon the exterior surface of the trim configuration, the stainless steelmaterial provides the trim with a corrosion-resistant surface ofattractive color and luster. The intermediate mild steel layer of thecomposite material provides the trim with adequate strength at low cost,and the opposite outer surface layer of aluminum material galvanicallyprotects the mild steel layer of the trim, as well as the steel of theautomotive body to which the trim is attached, by serving as apreferentially corrosive or sacrificial layer of material. That is, whenstainless steel trim material is mounted on an automotive body and isexposed to rain, road salts and the like, these extraneous materialstend to induce an electrolytic action between the stainless steel trimmaterial and the steel of the automotive body leading to rapid corrosionand rusting of the automotive body. When the trim material incorporatesa mild steel intermediate layer as above described, this electrolyticaction also tends to cause corrosion of the mild steel layer of thelaminate material resulting in further rust staining in the area of theautomotive trim. However, where the trim material further incorporatesan outer layer of aluminum material as above described, the aluminumlayer is corroded in preference to the steel of the automotive body orthe steel of the intermediate layer of the composite material, thiscorrosion resulting at worst in production of a white dust or powderwhich is easily removed from the trim area of the automotive body.

In order to enhance the usefulness of such a composite laminatematerial, particularly for use in forming relatively complex trimconfigurations, it would be desirable to achieve maximum formability inthe composite material. In addition it would also be desirable toenhance the scratch resistance of the stainless steel layer of thelaminate, which stainless steel layer ultimately forms the exteriorsurface of such trim configurations.

It is an object of this invention to provide a novel and improvedcomposite laminate material which is particularly suited for makingautomotive trim and the like; to provide automotive trim and the like inwhich the exterior surface of the trim has enhanced scratch resistance;to provide such com posite materials which are easily formed intorelatively complex trim configurations; and to provide such compositematerial and trim configurations which are of inexpensive construction.It is also an object of this invention to provide novel and improvedmethods for making such composite materials for use in making such trimconfigurations.

Other objects, advantages and details of the composite material, trimand methods of composite material manufacture as provided by thisinvention appear in the following detailed description of preferredembodiments of the invention, the detailed description referring to thedrawings in which:

FIG. l is a perspective view of the composite metal laminate material ofthis invention; and

FIG. 2 is a partial section view through an automotive body and the trimmaterial of this invention, the trim material being shown attached tothe automotive body.

Referring to the drawings, in FIG. 1 indicates the novel and improvedcomposite metal laminate material of this invention which is utilized inmaking automotive trim and the like in accordance with this invention.As shown, the laminate material incorporates a relatively thin outer orsurface layer 12 formed of stainless steel which is metallurgicallybonded along an interfacial surface 14 to a relatively much thicker intermediate layer 16 of a mild steel material. The laminate material 10further incorporates an opposite outer layer of aluminum material, thisopposite outer layer preferably being formed of a first layer 118 of onealuminum material metallurgically bonded to the intermediate layer 116along the interfacial surface 20 and a second layer 32 of anotheraluminum material metallurgically bonded to the layer 18 along theinterfacial surface 34 as shown in FIG. 1.

In the preferred embodiment of this invention, the stainless steel layerof the laminate material 10 embodies a chromium steel alloy such as iscommercially available under the designation SAE 434 Stainless Steel,this material having a nominal composition, by weight, of from 0.10 to0.14 percent carbon, from 14.0 to 18.0 percent chromium, and the balanceiron. However, other stainless steel materials, including nickel-bearingstainless steels, having a recrystallization temperature above about1,l00 F. can also be embodied in the laminate layer 12 within the scopeof this invention. It is also within the scope of this invention toutilize more than one layer of stainless steel material in the laminatelayer 112, these plural stainless steel layers being metallurgicallybonded together to serve as the single composite layer 112.

In the preferred embodiment of this invention, the intermediate laminatelayer 116 of this invention preferably embodies a mild steel materialwhich is commercially available under the designation SAE 1006 CappedSteel, this material having a composition, by weight, of 0.08 percent(maximum) carbon, 0.25-0.40 percent manganese, 0.040 percent (max imum)phosphorous, 0.050 percent (maximum) silicon, about 0.015 percent(maximum) aluminum, about 0.04 percent (maximum) copper, not more thanabout 0.39 percent of other ingredients present as impurities, and thebalance iron. Desirably this mild steel material has an uncombinednitrogen content up to about 0.009 percent by weight, this nitrogencontent replacing part of the iron content of the steel materiaPreferably, also, the material layer 116 embodied in the laminate 10preferably has a minimum thickness of at least about 0.0014 inch. Itshould be understood however that other mild steel materials havingrecrystallization temperatures not higher than about 1,050 F. can. alsobe utilized in the laminate layer 116 within the scope of thisinvention. It is also within the scope of this invention to utilize aplurality of mild steel layers which are metallurgically bonded togetherto serve as the single intermediate layer 16 of the composite material10. For example, in a practical embodiment of this invention, a layer ofSAE 1006 Capped Steel as above described is metallurgically bonded toanother mild steel layer and is incorporated in the composite material10 with the specifically named steel material disposed adjacent theinterfacial surface 20 of the composite material 10.

In accordance with this invention, the laminate layer 10 preferablyembodies a selected silicon aluminum alloy having a composition, byweight, of 0.01 percent copper, 0.46 percent iron, 0.01 percentmanganese, 0.02 percent titanium, 1.23 percent silicon, and the balancealuminum. However, other silicon aluminum alloys having between 0.7percent and about 3.0 percent silicon can also be embodied in thelaminate layer 18 within the scope of this invention.

In the preferred embodiment of this invention, the laminate layer 32 ofthe composite material 10 embodies any conventional, commerciallyavailable aluminum alloy such as the alloy designated by the US.Government as Aluminum Alloy 3003 having a composition, by weight, offrom 1.0-1.5 percent manganese, O.6 percent (maximum) silicon, 0.7percent (maximum) iron, 0.20 percent (maximum) copper, 0.10 percent(maximum) zinc, 0.05 percent (maximum) of each other element the totalof which shall not exceed 0.15 percent, and the balance aluminum.Commercially pure aluminum can also be embodied in the layer 32. Itshould be understood that the layer 32 can be omitted within the scopeof this invention, the entire outer aluminum layer of laminate materialbeing formed of the silicon aluminum alloy above described. As will beunderstood, the described aluminum layers 18 and 32 of the compositematerial are higher (more anodic) in the galvanic series of metals andalloys than the described stainless steel materials.

In accordance with the method of this invention, strips of the notedstainless steel, mild steel and aluminum materials are roll-squeezedtogether with reduction in the thickness of the metal layers formetallurgically bonding the metal layers together. The roll squeezing ispreferably performed while the materials are at a temperature below thetemperature at which a liquid phase of the strip materials is formed andbelow the temperature at which aluminum-iron intermetallic compounds areformed. For example, the material layers are preferably bonded togetherin the manner described in U.S. Pat. 2,691,815 issued the assignee ofthe present invention on Oct. 19, 1954. That is, for example, a strip ofSAE 434 Stainless Steel, a strip of SAE 1006 Capped Steel, a strip ofthe above described silicon aluminum alloy, and a strip of 3003 AluminumAlloy are preferably cleaned in the manner described in said U.S. Patentand are then squeezed together at room temperature, or at a temperatureslightly above room temperature as developed by the squeezing process,to achieve about 4575 percent reduction in the thickness of the stripmaterials, thereby to metallurgically bond the strip materials togetherin the solid phase. The starting strip materials are preferably inannealed, dead soft condition.

In accordance with this invention, the bonded composite material is thenheated to a temperature which is above the recrystallization temperatureof the mild steel material or materials in the intermediate laminatelayer 16 but which is below the recrystallization temperature of thestainless steel material or materials of the laminate layer 12 and whichis below the temperature at which aluminum-iron intermetallic compoundsare formed along the laminate interface 20 at any substantial rate. Forexample, where the SAE 434, SAE 1006, silicon aluminum alloy and 3003Aluminum materials specifically described above are embodied in thecomposite material 10, the composite material is heated to a temperaturein the range from about 900 F. to about 1,050 F. for sufficient periodof time, on the order of 15 minutes to about 6 hours, to substantiallyanneal the mild steel intermediate layer materials of the compositewhile leaving the stainless steel layer materials of the laminate insubstantially the cold-worked condition resulting from the initialroll-bonding of the laminate and while avoiding formation of anysignificant quantity of aluminum-iron intermetallic compounds along thelaminate interface 20. As will be understood, the uncombined nitrogencontent of the mild steel layer 16 bonded to the aluminum layer 18 tendsto retard the formation of aluminum-iron intermetallic compounds at thelaminate interface 20 so that, where the uncombined nitrogen content ofthe mild steel materials of the laminate is at the upper end of therange suggested herein, the heat treatment of the bonded compositematerial can best be performed at the upper range of the temperaturessuggested herein. As will also be understood, this heating step does notproduce a liquid phase in any of the composite layer materials but tendsto sinter the laminate bonds in the manner described in the above notedU.S. Patent for enhancing the strength of the bonds between the laminatelavers.

In a preferred embodiment of this invention for use in making automotivetrim and the like, the laminate material 10 has a thickness in the rangefrom about 0.015 to 0.063 inch, the stainless steel layer 12 comprisingabout 15 percent, the mild steel layer 16 comprising about 80 percent,and the aluminum layers 18 and 32 comprising a total of about percent ofthe total laminate thickness. In this arrangement, the aluminum layer 18of the laminate preferably has a thickness of at least about 0.002 inch.

In accordance with this invention, the composite material is formed intoany desired trim configuration such as is illustrated in FIG. 2 in whichthe stainless steel layer of the laminate is disposed exteriorly of thetrim configuration. That is, for example, as shown in FIG. 2, thelaminate material is formed by any conventional method into the C-shapedconfiguration illustrated at 22. This trim configuration 22 is thensecured to an automotive body 24 formed of mild steel and the like by aclip 26 which is also preferably formed of steel,

plastic or the like, the body 24 customarily having a painted coating 28thereon and the clips being secured to the body by means of a steel orplastic rivet 30 or the like as shown in FIG. 2. In this arrangement,the clip 26 has a flat portion 26.1 resting against the paintedautomotive body, has winged portions 26.2 extending in spaced relationto the body, and has inturned edges 26.3, the ends 22.1 of the trimconfiguration being fitted behind the clipped wings 26.2 for detachablysecuring the trim to the automotive body.

In the laminate material 10 provided by this invention, the interface 20in the laminate is free of any significant aluminum-iron intermetalliccompound and the principal layer 16 of the laminate is in annealedcondition so that the laminate is easily formed into the described trimconfiguration as well as other trim configurations. Although thestainless steel layer 12 of the laminate is in cold-worked condition, itis found that this cold-worked layer is readily formed when bonded inthe described manner to the annealed mild steel layer of the laminate.Yet the resulting trim configuration has significant advantages in thatthe cold-worked stainless steel surface layer of the laminate does nottend to be deleteriously affected by the forming operations necessaryfor making the trim configuration and the stainless steel layer alsoretains its attractive color and luster. The stainless steel layer ofthe trim is also highly resistant to abrasion or scratching because ofits cold-worked condition. The inner aluminum layer or layers of thelaminate are disposed as sacrificial layers to be corroded during use ofthe trim material in preference to the mild steel materials of thelaminate or of the automotive body, thereby protecting these mild steelmaterials against galvanic corrosion. That is, the aluminum layers ofthe laminate material being higher (more anodic) in the galvanic seriesof metals and alloys than the mild steel materials of the laminate, anygalvanic corrosion occurring in the area of the trim configurationpreferentially corrodes the aluminum materials of the trimconfiguration. The aluminum layers of the laminate are very thin so thatcorrosion thereof does not significantly alter the fit of the trimconfiguration on the clip 26.

Although particular embodiments of the laminate materials, trims andmethods of this invention have been described by way of illustration, itshould be understood that this invention includes all modifications andequivalents thereof which fall within the scope of the appended claims.

Iclaim:

l. A method for making a composite metal laminate material comprisingdisposing a strip of mild steel material between a strip of stainlesssteel material and a strip of aluminum material to engage interfacialsurfaces of said strips, said interfacial surfaces of said strips beingclean and free of bond-deterring contaminants, roll-squeezing saidstrips together with reduction in the thicknesses thereof at atemperature below the temperature at which a liquid phase of said stripmaterials is formed and below a temperature at which aluminum-ironintermetallic compounds are formed between the strip materials forbonding said strip means together to form a composite material and forcold-working said stainless steel material, and heating said compositematerial to a temperature which is above the recrystallizationtemperature of said mild steel material and which is below therecrystallization temperature of said stainless steel material and belowthe temperature at which aluminum-iron intermetallic compounds areformed at the interface between said mild steel and aluminum materialsto recrystallize said mild steel while retaining said stainless steelmaterial in cold-worked condition.

2. A method as set in claim 1 wherein said strip of mild steel materialis of sufficient thickness to form about percent of the total thicknessof said composite material.

3. A method as set forth in claim 1 wherein said strip of mild steelmaterial includes a layer of mild steel material having a composition,by weight, of 0.08 percent maximum) carbon, 0.25-0.40 percent manganese,0.040 percent (maximum) phosphorous, 0.050 percent (maximum) silicon,about 0.015 percent (maximum) aluminum, about 0.04 percent (maximum)copper, not more than about 0.39 percent of other ingredients present asimpurities, and the balance iron, and wherein said strip of aluminummaterial includes a layer of silicon aluminum alloy having acomposition, by weight, of 0.01 percent copper, 0.46 percent iron, 0.01percent manganese, 0.02 percent titanium, 1.23 percent silicon, and thebalance aluminum, said strip of mild steel material and said strip ofaluminum material being disposed to engage an interfacial surface ofsaid layer of said mild steel material with an interfacial surface ofsaid layer of silicon aluminum alloy and being rolled-squeezed formetallurgically bonding said layer of mild steel material to said layerof silicon aluminum alloy along said interfacial surfaces of saidlayers.

4. A method for making a composite metal laminate material comprisingthe steps of providing a strip of mild steel material having acomposition, by weight, of 0.08 percent (maximum) carbon, 0.25-0.40percent manganese, 0.040 percent (maximum) phosphorous, 0.050 percent(maximum) silicon, about 0.015 percent (maximum) aluminum, about 0.04percent (maximum) copper, not more than about 0.39 percent of otheringredients present as impurities, and the balance iron, providing astrip of stainless steel material having a composition, by weight, offrom 0.10-0.l4 percent carbon, from l4.0l 8.0 percent chrominum, and thebalance iron, providing a strip of silicon aluminum alloy having acomposition, by weight, of 0.01 percent copper, 0.46 percent iron, 0.01percent manganese, 0.02 percent titanium, 1.23 percent silicon, and thebalance aluminum, providing a strip of another aluminum material havinga composition, by weight, of from 1.0-1.5 percent manganese, 0.6 percent(maximum) silicon, 0.7 percent (maximum) iron, 0.20 percent (maximum)copper, 0.10 percent (maximum) zinc, 0.05 percent (maximum) of eachother element the total of which will not exceed 0.15 percent, and thebalance aluminum, disposing said strip of mild steel material betweensaid strip of stainless steel and said strip of silicon aluminum alloyto engage interfacial surfaces of said strips, and disposing said stripof other aluminum material to engage an opposite interfacial surface ofsaid layer of silicon aluminum alloy, said interfacial surfaces of saidstrips being clean and free of bond-deterring contaminants,roll-squeezing said strips together with reduction in the thicknessesthereof at a temperature below the temperature at which a liquid phaseof said strip material is formed and below a temperature at whichaluminum-iron intermetadlic compounds are formed between said mild steeland silicon aluminum alloy strip materials for bonding said stripstogether to form a composite material and for cold-working saidstainless steel material, and heating said composite material to atemperature in the range from 900 to 1,050 F. to recrystallize said mildsteel material while retaining said stainless steel material incold-worked condition and while retaining said interfacial surfacebetween said mild steel and silicon aluminum alloy materialssubstantially free of aluminum-iron intermetallic compounds.

a a =1: s =1:

2. A method as set in claim 1 wherein said strip of mild steel materialis of sufficient thickness to form about 80 percent of the totalthickness of said composite material.
 3. A method as set forth in claim1 wherein said sTrip of mild steel material includes a layer of mildsteel material having a composition, by weight, of 0.08 percent(maximum) carbon, 0.25-0.40 percent manganese, 0.040 percent (maximum)phosphorous, 0.050 percent (maximum) silicon, about 0.015 percent(maximum) aluminum, about 0.04 percent (maximum) copper, not more thanabout 0.39 percent of other ingredients present as impurities, and thebalance iron, and wherein said strip of aluminum material includes alayer of silicon aluminum alloy having a composition, by weight, of 0.01percent copper, 0.46 percent iron, 0.01 percent manganese, 0.02 percenttitanium, 1.23 percent silicon, and the balance aluminum, said strip ofmild steel material and said strip of aluminum material being disposedto engage an interfacial surface of said layer of said mild steelmaterial with an interfacial surface of said layer of silicon aluminumalloy and being rolled-squeezed for metallurgically bonding said layerof mild steel material to said layer of silicon aluminum alloy alongsaid interfacial surfaces of said layers.
 4. A method for making acomposite metal laminate material comprising the steps of providing astrip of mild steel material having a composition, by weight, of 0.08percent (maximum) carbon, 0.25-0.40 percent manganese, 0.040 percent(maximum) phosphorous, 0.050 percent (maximum) silicon, about 0.015percent (maximum) aluminum, about 0.04 percent (maximum) copper, notmore than about 0.39 percent of other ingredients present as impurities,and the balance iron, providing a strip of stainless steel materialhaving a composition, by weight, of from 0.10-0.14 percent carbon, from14.0-18.0 percent chromimum, and the balance iron, providing a strip ofsilicon aluminum alloy having a composition, by weight, of 0.01 percentcopper, 0.46 percent iron, 0.01 percent manganese, 0.02 percenttitanium, 1.23 percent silicon, and the balance aluminum, providing astrip of another aluminum material having a composition, by weight, offrom 1.0-1.5 percent manganese, 0.6 percent (maximum) silicon, 0.7percent (maximum) iron, 0.20 percent (maximum) copper, 0.10 percent(maximum) zinc, 0.05 percent (maximum) of each other element the totalof which will not exceed 0.15 percent, and the balance aluminum,disposing said strip of mild steel material between said strip ofstainless steel and said strip of silicon aluminum alloy to engageinterfacial surfaces of said strips, and disposing said strip of otheraluminum material to engage an opposite interfacial surface of saidlayer of silicon aluminum alloy, said interfacial surfaces of saidstrips being clean and free of bond-deterring contaminants,roll-squeezing said strips together with reduction in the thicknessesthereof at a temperature below the temperature at which a liquid phaseof said strip material is formed and below a temperature at whichaluminum-iron intermetallic compounds are formed between said mild steeland silicon aluminum alloy strip materials for bonding said stripstogether to form a composite material and for cold-working saidstainless steel material, and heating said composite material to atemperature in the range from 900* to 1,050* F. to recrystallize saidmild steel material while retaining said stainless steel material incold-worked condition and while retaining said interfacial surfacebetween said mild steel and silicon aluminum alloy materialssubstantially free of aluminum-iron intermetallic compounds.